Network Working Group F. L. Templin, Ed.
Internet-Draft Boeing Research & Technology
Updates: 6864, 8200, 8900 (if approved) 8 September 2023
Intended status: Standards Track
Expires: 11 March 2024
Identification Extension for the Internet Protocol
draft-templin-intarea-ipid-ext-08
Abstract
The Internet Protocol, version 4 (IPv4) header includes a 16-bit
Identification field in all packets, but this length is too small to
ensure reassembly integrity even at moderate data rates in modern
networks. Even for Internet Protocol, version 6 (IPv6), the 32-bit
Identification field included when a Fragment Header is present may
be smaller than desired for some intended uses. This specification
addresses these limitations by defining both an IPv4 header option
and an IPv6 Extended Fragment Header for Identification Extension.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 11 March 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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extracted from this document must include Revised BSD License text as
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. IPv4 ID Extension . . . . . . . . . . . . . . . . . . . . . . 4
5. IPv4 ID Hyper-Extension . . . . . . . . . . . . . . . . . . . 5
6. IPv6 ID Extension . . . . . . . . . . . . . . . . . . . . . . 6
7. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7
8. IPv4 ID Applications . . . . . . . . . . . . . . . . . . . . 8
9. IPv4 Parcel Index Extension . . . . . . . . . . . . . . . . . 9
10. IPv6 Network Fragmentation . . . . . . . . . . . . . . . . . 9
11. Packet Too Big (PTB) Extensions . . . . . . . . . . . . . . . 10
12. A Note on Fragmentation Considered Harmful . . . . . . . . . 12
13. Implementation Status . . . . . . . . . . . . . . . . . . . . 12
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
15. Security Considerations . . . . . . . . . . . . . . . . . . . 13
16. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
17. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
17.1. Normative References . . . . . . . . . . . . . . . . . . 14
17.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 16
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
The Internet Protocol, version 4 (IPv4) header includes a 16-bit
Identification in all packets [RFC0791], but this length is too small
to ensure reassembly integrity even at moderate data rates in modern
networks [RFC4963] [RFC6864][RFC8900]. This document defines a new
option for IPv4 that extends the Identification field to 32-bits
(i.e., the same as for IPv6 packets that include a standard Fragment
Header [RFC8200]) to support reassembly integrity at higher data
rates.
When an IPv4 packet includes this "Identification Extension" option,
the value encoded in the IPv4 header Identification field represents
the 2 least-significant octets while the option encodes the 2 most-
significant octets of an extended 4-octet Identification. Hosts and
routers that recognize the option employ it for packet identification
purposes in general and to fortify the IPv4 reassembly procedure in
particular.
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This specification also supports a "hyper-extended" mode that extends
the Identification field further for both IPv4 and IPv6. This format
may be useful for networks that operate at extreme data rates, or for
other cases when Identification uniqueness assurance is critical.
Together, these extensions ensure robust reassembly integrity as well
as Identification uniqueness for the Internet.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document uses the term "IP" to refer generically to either
protocol version (i.e., IPv4 or IPv6), and uses the term "IP ID" to
refer generically to the IP Identification field whether in simple or
(hyper-)extended form.
The terms "Maximum Transmission Unit (MTU)", "Effective MTU to
Receive (EMTU_R)" and "Maximum Segment Lifetime (MSL)" are used
exactly the same as for standard Internetworking terminology.
The term "Packet Too Big (PTB)" refers to either an IPv6 "Packet Too
Big" [RFC8201][RFC4443] or an IPv4 "Destination Unreachable -
Fragmentation Needed" [RFC1191] message.
3. Motivation
Studies over many decades have shown that upper layer protocols can
achieve greater performance by configuring segment sizes that exceed
the path Maximum Transmission Unit (MTU). When the segment size
exceeds the path MTU, IP fragmentation at some layer is a natural
consequence. However, the 2-octet (16-bit) IPv4 and 4-octet (32-bit)
IPv6 Identification fields may be too short to support reassembly
integrity at sufficiently high data rates. This specification
therefore proposes to fortify the IP ID by extending its length.
A recent study [I-D.templin-dtn-ltpfrag] proved that configuring
segment sizes that cause IPv4 packets to exceed the path MTU (thereby
invoking IPv4 fragmentation and reassembly) provides a multiplicative
performance increase at high data rates in comparison with using
smaller segment sizes as long as fragment loss is negligible. This
contradicts decades of unfounded assertions to the contrary and
proves that the original design of the Internet which included
fragmentation and reassembly as core functions was the correct one.
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An alternative to extending the IP ID was also examined in which IPv4
packets were first encapsulated in IPv6 headers then subjected to
IPv6 fragmentation where a 4-octet Identification field already
exists. While this IPv4-in-IPv6 encapsulation followed by IPv6
fragmentation also showed a performance increase for larger segment
sizes in comparison with using MTU-sized or smaller segments, the
magnitude of increase was significantly less than for invoking IP
fragmentation directly without first applying encapsulation.
Widely deployed implementations also often employ a common code base
for both IPv4 and IPv6 fragmentation/reassembly since their
algorithms are so similar. It therefore seems reasonable to conclude
that IPv4 fragmentation and reassembly can support higher data rates
than IPv6 when full (uncompressed) headers are used, while the rates
may be similar when IPv6 header compression is applied.
In addition to enabling higher data rates in the presence of
fragmentation and reassembly, extending the IP ID can enable other
important services. For example, an extended IP ID can support a
duplicate packet detection service in which the network remembers
recent IP ID values for a flow to aid detection of potential
duplicates (note however that the network layer must not incorrectly
flag intentional lower layer retransmissions as duplicates). An
extended IP ID can also provide a packet sequence number that allows
communicating peers to exclude any packets with IP ID values outside
of a current window as potential spurious transmissions. These and
other cases also hold true even if the source frequently resets its
starting IP ID sequence numbers to maintain an unpredictable profile.
For these reasons, it is clear that a robust IP fragmentation and
reassembly service can provide a useful tool for performance
maximization in the Internet and that an extended IP ID can provide
greater uniqueness assurance. This document therefore presents a
means to extend the IP ID to better support these services.
4. IPv4 ID Extension
IP ID extension for IPv4 is achieved by introducing a new IPv4
option. This new IPv4 ID Extension (IDEXT) Option begins with an
option-type octet with "copied flag" set to '1', "option class" set
to '00' and "option number" set to TBD. The option-type octet is
followed immediately by an option-length octet set to the constant
value '4'.
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The option-type is then followed by a 2-octet "ID Extension" field
that (when combined with the 2 least-significant octets found in the
IPv4 packet header Identification field) includes the 2 most-
significant octets of an extended 4-octet (32-bit) IP ID for the
packet. The option format is shown in Figure 1:
+--------+--------+--------+--------+
|100[TBD]|00000100| ID Extension |
+--------+--------+--------+--------+
Type=TBD Length=4
Figure 1: IPv4 ID Extension (IDEXT) Option
When an IPv4 source node (i.e., an original source or an IPv4
encapsulation ingress) wishes to supply a 4-octet extended IP ID for
the packet, it includes an IDEXT option in the IPv4 packet header
options area, i.e., based on the same rules as for including any IPv4
option. The source next writes the 2 least-significant octets in the
IPv4 header Identification field and writes the 2 most-significant
octets in the "ID Extension" field.
The source then applies source fragmentation if necessary while
including the extended IP ID value. The source copies the ID
Extension option to each resulting fragment and sets or clears the
"Don't Fragment (DF)" flag as desired.
The source then forwards each packet/fragment to the next hop, where
IPv4 forwarding will direct them toward the final destination. If an
IPv4 router on the path needs to apply network fragmentation, it
copies the IDEXT option into each resulting fragment to provide the
final destination with the correct reassembly context.
5. IPv4 ID Hyper-Extension
When an IPv4 source produces a sustained burst of IPv4 packets that
use the same source address, destination address and protocol at
extreme data rates (e.g., in excess of 1Tbps), or when the source
plans to reset the IP ID starting sequence to a new pseudo-random
value frequently, it can optionally "hyper-extend" the IP ID by
supplying an 8-octet (64-bit), 12-octet (96-bit) or 16-octet
(128-bit) value instead of a 2/4-octet value.
To apply hyper-extension, the source includes an IDEXT option with
option-type set to TBD the same as above, but with option-length set
to '8', '12' or '16' instead of '4' as shown in Figure 2:
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+--------+--------+
|100[TBD]| Length |
+--------+--------+--------+--------+
~ ID Extension ~
+--------+--------+--------+--------+
Type=TBD Length=8, 12 or 16
Figure 2: IDEXT Option with Hyper-Extension
The option will then include a 6, 10 or 14-octet ID Extension, with
the most significant IP ID octets appearing in network byte order in
the option-data and with the 2 least significant octets appearing in
the IPv4 Identification field. For a 6-octet extension, the 8-octet
IP ID can then fit properly within the longest word length for modern
64-bit architectures.
6. IPv6 ID Extension
Techniques that improve IPv4 often also apply in a corresponding
fashion for IPv6 (and vice-versa). The same is also true for IPv6 ID
Extensions.
For a 4-octet Identification value in IPv6, nodes simply include a
standard IPv6 Fragment Header as specified in [RFC8200] with the
"Fragment Offset" field and "M" flag set either to values appropriate
for a fragmented packet or the value '0' for an unfragmented packet.
The node then includes a 4-octet Identification value for the packet.
For 8-octet or 12-octet Identification values, this document defines
a new IPv6 Extended Fragment Header. The IPv6 Extended Fragment
Header is identified by the Next Header type value 'TBD2' (see: IANA
Considerations) and the format is shown in Figure 3:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Reserved | Fragment Offset |Res|M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Identification (12 octets) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: IPv6 Extended Fragment Header
In the above format, the control values in the first four octets are
interpreted exactly the same as for the standard IPv6 Fragment
Header, while the Identification field is 12 octets in length and
encodes a 96-bit value in network byte order. (When only a 64-bit
Identification is needed, the most significant 32 Identification bits
are set to '0'.)
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For both the Standard and Extended IPv6 Fragment Header, this
document further specifies a new coding for the 3 least significant
("flag") bits of the control field as shown in Figure 4:
2 3 3
9 0 1
+---+---+---+
| | F | M |
| 0 | P | F |
+---+---+---+
Figure 4: Fragmentation Flag Bits
In this new coding, Bit 31 remains as the "More Fragments (MF)" flag,
while bit 30 is re-defined as the "Fragmentation Permitted (FP)" flag
and bit 29 remains as a Reserved flag set to 0. When bit 30 is set
to 0, network intermediate systems are not permitted to fragment the
packet. When bit 30 is set to 1, network fragmentation is permitted.
7. Requirements
IPv4 routers MUST forward without dropping any packets with IPv4
option-type TBD while copying the option during network
fragmentation, and IPv6 routers MUST forward without dropping any
packets with IPv6 Next Header type TBD2.
IPv6 sources MUST include at most one Standard or Extended Fragment
Header in a single packet. IPv6 intermediate systems and destination
MUST silently drop any packets that include multiple Fragment Headers
whether Standard or Extended.
Destinations that recognize IPv4 option-type TBD MUST accommodate
packets that include all (hyper-)extended IP ID formats based on any
4/8/12/16-octet value included by the source.
Sources MUST transmit and destinations MUST process the octets of the
extended IP ID in network byte order with the base IP header
Identification field containing the least significant octets and the
ID Extension field containing the most significant octets.
Implementations maintain the IP ID as a 16-octet (128-bit) integer
with any most significant octets not included in an extension set to
0.
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Destinations MUST be capable of reassembling packets as large as the
minimum Effective MTU to Receive (EMTU_R) specified for IPv4
([RFC1122], Section 3.3.2) or IPv6 ([RFC8200], section 5).
Destinations that recognize extended IP IDs SHOULD configure and
advertise the largest possible EMTU_R (65535 octets maximum) and MAY
dynamically advertise a reduced EMTU_R during periods of reassembly
buffer congestion (see: Section 11).
When a destination reassembles an IP packet with an extended IP ID
that arrived as fragments, it returns an EMTU_R indication to the
source (subject to rate limiting) according to its current reassembly
buffer congestion conditions (see: Section 11). While a source
continues to receive these indications, it can continue to send
fragmented or fragmentable packets no larger than the EMTU_R at rates
within the Maximum Segment Lifetime (MSL) wraparound threshold for
the extended IP ID length; otherwise, the source must assume the MSL
threshold for the non-extended Identification field length [RFC6864].
(When the source includes sufficiently strong integrity checks that
the destination can use to detect reassembly errors, however, it can
continue to send at higher data rates regardless of the MSL.)
Extended IP ID formats supported by this specification include only
the mandatory-to-implement (hyper-)extended formats which are
differentiated by the option-length value for IPv4 or the extension
header type for IPv6. Future documents may specify additional
formats with different option length values.
Note: IP fragmentation can only be applied for packet lengths up to a
maximum of 65535 octets. IP parcels and advanced jumbos provide a
means for efficiently packaging and shipping multiple large segments
or truly large singleton segments in IP packets that may exceed this
size [I-D.templin-intarea-parcels].
8. IPv4 ID Applications
[RFC6864] limits the use of the IPv4 ID field to only supporting the
fragmentation and reassembly processes. When an IPv4 packet includes
a TBD option, however, the source asserts that the IPv4 ID includes a
well-managed extended-length value that can satisfy uniqueness
properties useful for other purposes.
This specification therefore updates [RFC6864] by permitting use of
the extended IPv4 ID for purposes other than support for
fragmentation and reassembly.
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9. IPv4 Parcel Index Extension
[I-D.templin-intarea-parcels] specifies procedures for fragmenting
and reassembling the constituent packets derived from IP parcels that
have been opened somewhere along the path. Since each packet derived
from the same parcel shares the same Identification value, an
ancillary (Parcel) Index field is also necessary to differentiate the
packets.
The IPv6 Fragment Header includes an 8-bit Reserved field that can be
re-purposed to encode an Index, but the IPv4 header does not provide
sufficient space. With reference to Section 4 and Section 5, this
document therefore specifies the following IPv4 ID Parcel Index
extension octet:
+-+-+-+-+-+-+-+-+
| Index |P|S|
+-+-+-+-+-+-+-+-+
Figure 5: IPv4 ID Parcel Index Extension Octet
When the IPv4 TBD option-length is '5', the option-data includes 2
Identification extension octets followed by the Parcel Index
extension octet. When option-length is '9', '13', or '17', the
option-data instead includes 6, 10 or 14 Identification extension
octets followed by the Parcel Index extension octet.
The Parcel Index octet field names and descriptions appear in
[I-D.templin-intarea-parcels].
10. IPv6 Network Fragmentation
When an IPv6 router forwards a packet that includes an (Extended)
Fragment Header, it applies (further) fragmentation if the next hop
link MTU is insufficient and if the "Fragmentation Permitted (FP)"
flag is set to '1' (see: Section 6).
The "Fragmentation Permitted (FP)" flag for IPv6 therefore provides a
"network fragmentation permitted" indication in the same spirit as
the "Don't Fragment (DF)" flag for IPv4. This allows IPv6
intermediate systems to apply fragmentation on packets that already
include an (Extended) Fragment Header, but never to insert an
(Extended) Fragment Header themselves.
This specification therefore updates [RFC8200] by permitting network
fragmentation for IPv6 under the above conditions.
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11. Packet Too Big (PTB) Extensions
When a node forwards an IP packet that exceeds the next hop link MTU
but for which fragmentation is forbidden, it drops the packet and
returns a "Packet Too Big (PTB)" message to the original source
[RFC1191][RFC4443][RFC8201]. This always results in wasted
retransmissions by the source as well as all intermediate systems on
the path toward the node with the restricting link. Conversely, when
a packet includes an extended IP ID the network will perform
fragmentation if necessary allowing the packet to reach the final
destination without loss due to a size restriction.
While the fragmentation and reassembly processes eliminate wasted
retransmissions and can also support significant performance gains
through transmissions of upper layer protocol segment sizes that
exceed the path MTU, the processes sometimes represent pain points
that should be communicated to the original source. The original
source should then take measures to reduce the pain.
The IPv4 PTB format includes an "unused" field while the IPv6 PTB
format includes a "Code" field, with both fields set to the value "0"
for ordinary PTB messages. The value "0" signifies a "classic" PTB
and always denotes that the subject packet was unconditionally
dropped due to a size restriction. For IP packets that include an IP
ID Extension option (and also a Fragment Header for IPv6) other PTB
unused/Code values are defined as follows:
1 - Sent by an intermediate system when it performs fragmentation
on an IP packet that could instead have been fragmented to a
smaller fragment size by the original source. The system sends
the PTB message subject to rate limiting while still fragmenting
and forwarding the packet. The MTU field of the PTB message
includes the maximum fragment size that can pass through the
restricting link. This value will often be considerably smaller
than the maximum packet size that can be reassembled by the final
destination.
2 - The same as for value 1, except that the intermediate system
drops the packet instead of fragmenting and forwarding. This
message type represents a hard error.
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3 - Sent by the final destination when it performs reassembly on a
packet with an extended IP ID subject to rate limiting. The
destination sends the PTB message while still reassembling and
accepting the packet. The MTU field of the PTB message includes
the largest possible EMTU_R value under current reassembly buffer
congestion constraints. This value must be no smaller than the
minimum EMTU_R for the IP protocol version and will often be
considerably larger than the path MTU.
4 - The same as for value 3, except that the final destination
drops the packet instead of reassembling and accepting. This
message type represents a hard error.
5 - Parcel Report - Sent by an intermediate system or final
destination in response to an IP parcel that triggered the event
(see: [I-D.templin-intarea-parcels]).
6 - Jumbo Report - Sent by an intermediate system or final
destination in response to an IP advanced jumbo that triggered the
event (see: [I-D.templin-intarea-parcels]).
When the original source receives an authentic Code 1 or 2 PTB, it
begins to perform source fragmentation using the fragment size
indicated in the MTU field which may be smaller than the first hop
link MTU. This reduces the burden on intermediate systems in the
path which will see a reduced dependence on network fragmentation.
When the original source receives a Code 3 or 4 PTB, it limits the
size of the packets it sends based on the EMTU_R size found in the
MTU field which may be larger than the path MTU.
When the original source ceases to receive Code 3 or 4 PTB messages,
it must assume that the destination no longer recognizes IP ID
extensions and must then impose rate limiting based on the wraparound
threshold for a non-extended Identification within the MSL [RFC6864].
These rate limitations can be relaxed when the source can include an
integrity check which the destination can verify.
When an intermediate system or destination returns a Code 1-6 PTB, it
prepares an ICMPv6 PTB message [RFC4443] and with MTU set as
discussed above. The node then writes its own IP address as the PTB
source and writes the source address of the packet that invoked the
report as the PTB destination (for IPv4, the node writes the PTB
address as an IPv4-Compatible IPv6 address [RFC4291]).
The node next copies as much of the leading portion of the invoking
packet as possible (beginning with the IP header) into the "packet in
error" field without causing the entire PTB (beginning with the IPv6
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header) to exceed 256 octets in length. The node then sets the
ICMPv6 Checksum field to 0 instead of calculating and setting a true
checksum since the UDP checksum (see below) already provides an
integrity check.
Since IPv6 packets cannot transit IPv4 paths, and since middleboxes
often filter ICMPv6 messages as they transit IPv6 paths, the node
next wraps the ICMPv6 PTB message in UDP/IP headers of the correct IP
version with the IP source and destination addresses copied from the
PTB and with UDP port numbers set to the OMNI UDP port number
[I-D.templin-intarea-omni]. The node then calculates and sets the
UDP Checksum (and for IPv4 clears the DF bit). The node finally
sends the prepared PTB to the original source.
Note: This implies that original sources that send packets with
extended IP IDs must be capable of accepting and processing these
OMNI protocol UDP messages. A source that sends packets with
extended IP IDs must therefore implement enough of the OMNI interface
to be able to recognize and process these messages.
12. A Note on Fragmentation Considered Harmful
During the earliest days of the Internet, researchers made the
profound statement that fragmentation should be deemed "harmful"
based on empirical observations in the ARPAnet, DARPA Internet and
other internetworks of the day [KENT87]. These observations somehow
inspired a discipline known as "Path MTU Discovery" within a new
community known as the Internet Engineering Task Force (IETF). In
more recent times, the IETF amplified these earlier assertions in "IP
Fragmentation Considered Fragile" [RFC8900].
Rather than encourage implementation improvements from the very
beginning, however, the IETF somehow forgot that IP fragmentation and
reassembly were still fundamental elements of the Internet
architecture. This has resulted in a modern Internet where path MTU
discovery (including its more recent derivatives) provides a poor
service especially for dynamic networks with path MTU diversity.
This document introduces a more robust solution based on a properly
functioning IP fragmentation and reassembly service as intended in
the original architecture. This document therefore updates
[RFC8900].
13. Implementation Status
In progress.
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14. IANA Considerations
IANA is requested to assign a new IPv4 Option named "IDEXT" in the
'ip-parameters' registry (registration procedures not defined). The
option sets "Copy" to '1', "Class" to '00' and "Number" to TBD.
IANA is further requested to assign a new Protocol Number TBD2 in the
in the 'protocol-numbers' registry (registration procedures IESG
Approval or Standards Action). The registry sets Decimal to "TBD2",
Keyword to "IPv6-XFrag", Protocol to "Extended Fragment Header for
IPv6" and IPv6 Extension Header to "Y".
The IANA is instructed to assign new Code values in the "ICMPv6 Code
Fields: Type 2 - Packet Too Big" registry (registration procedure is
Standards Action or IESG Approval). The registry should appear as
follows:
Code Name Reference
--- ---- ---------
0 PTB Hard Error [RFC4443]
1 Fragmentation Needed (soft) [RFCXXXX]
2 Fragmentation Needed (hard) [RFCXXXX]
3 Reassembly Needed (soft) [RFCXXXX]
4 Reassembly Needed (hard) [RFCXXXX]
5 Parcel Report [RFCXXXX]
6 Jumbo Report [RFCXXXX]
Figure 6: ICMPv6 Code Fields: Type 2 - Packet Too Big Values
(Note: this registry also defines values for the "unused" field of
ICMPv4 "Destination Unreachable - Fragmentation Needed" messages.)
15. Security Considerations
All aspects of IP security apply equally to this document, which does
not introduce any new vulnerabilities. Moreover, when employed
correctly the mechanisms in this document robustly address a known
IPv4 reassembly integrity concern [RFC4963] and also provide an
advanced degree of packet uniqueness assurance.
16. Acknowledgements
This work was inspired by continued DTN performance studies. Bob
Hinden and Tom Herbert offered useful insights that helped improve
the document.
17. References
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17.1. Normative References
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>.
[RFC1122] Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122,
DOI 10.17487/RFC1122, October 1989,
<https://www.rfc-editor.org/info/rfc1122>.
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990,
<https://www.rfc-editor.org/info/rfc1191>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed.,
"Path MTU Discovery for IP version 6", STD 87, RFC 8201,
DOI 10.17487/RFC8201, July 2017,
<https://www.rfc-editor.org/info/rfc8201>.
17.2. Informative References
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Internet-Draft IP Identification Extension September 2023
[I-D.templin-dtn-ltpfrag]
Templin, F., "LTP Fragmentation", Work in Progress,
Internet-Draft, draft-templin-dtn-ltpfrag-10, 5 May 2023,
<https://datatracker.ietf.org/doc/html/draft-templin-dtn-
ltpfrag-10>.
[I-D.templin-intarea-omni]
Templin, F., "Transmission of IP Packets over Overlay
Multilink Network (OMNI) Interfaces", Work in Progress,
Internet-Draft, draft-templin-intarea-omni-31, 5 July
2023, <https://datatracker.ietf.org/doc/html/draft-
templin-intarea-omni-31>.
[I-D.templin-intarea-parcels]
Templin, F., "IP Parcels and Advanced Jumbos", Work in
Progress, Internet-Draft, draft-templin-intarea-parcels-
67, 30 August 2023,
<https://datatracker.ietf.org/doc/html/draft-templin-
intarea-parcels-67>.
[KENT87] Kent, C. and J. Mogul, ""Fragmentation Considered
Harmful", SIGCOMM '87: Proceedings of the ACM workshop on
Frontiers in computer communications technology, DOI
10.1145/55482.55524, http://www.hpl.hp.com/techreports/
Compaq-DEC/WRL-87-3.pdf.", August 1987.
[RFC4963] Heffner, J., Mathis, M., and B. Chandler, "IPv4 Reassembly
Errors at High Data Rates", RFC 4963,
DOI 10.17487/RFC4963, July 2007,
<https://www.rfc-editor.org/info/rfc4963>.
[RFC6814] Pignataro, C. and F. Gont, "Formally Deprecating Some IPv4
Options", RFC 6814, DOI 10.17487/RFC6814, November 2012,
<https://www.rfc-editor.org/info/rfc6814>.
[RFC6864] Touch, J., "Updated Specification of the IPv4 ID Field",
RFC 6864, DOI 10.17487/RFC6864, February 2013,
<https://www.rfc-editor.org/info/rfc6864>.
[RFC7126] Gont, F., Atkinson, R., and C. Pignataro, "Recommendations
on Filtering of IPv4 Packets Containing IPv4 Options",
BCP 186, RFC 7126, DOI 10.17487/RFC7126, February 2014,
<https://www.rfc-editor.org/info/rfc7126>.
[RFC8900] Bonica, R., Baker, F., Huston, G., Hinden, R., Troan, O.,
and F. Gont, "IP Fragmentation Considered Fragile",
BCP 230, RFC 8900, DOI 10.17487/RFC8900, September 2020,
<https://www.rfc-editor.org/info/rfc8900>.
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Appendix A. Change Log
<< RFC Editor - remove prior to publication >>
Differences from earlier versions:
* First draft publication.
Author's Address
Fred L. Templin (editor)
Boeing Research & Technology
P.O. Box 3707
Seattle, WA 98124
United States of America
Email: fltemplin@acm.org
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